However, it also has great limitations, for example, it can only calculate the spectral lines of hydrogen atoms and hydrogen-like atoms, but it can't do anything about other slightly complicated atoms; In addition, it has nothing to do with the intensity, width and polarization of spectral lines. Theoretically, the fundamental problem of this theory is that it is based on the classical theory, but it adds some important assumptions that are incompatible with the classical theory, such as steady-state radiation-free and quantization conditions, so it is far from a perfect theory.
However, Bohr's (and Sommerfeld's) theory explained the spectral experiment theoretically for the first time, and pointed out for the first time that the classical theory could not be fully applied to the internal motion process of atoms, revealing the unique quantization law of microscopic systems.
Therefore, it is an important milestone in the development history of atomic physics, which has greatly promoted the establishment of quantum mechanics theory in the future.
In addition, some basic concepts in Bohr's theory, such as "steady state", "energy level" and "energy level transition determines radiation frequency", are still very important basic concepts in quantum mechanics, although other concepts, such as orbit, have been proved not to be applicable to microscopic particles.